As time goes by, more and more altcoins are eroding away bitcoin shares in the total crypto currency realm. DRK is getting interesting at this moment.
Is it reasonable to have a altcoin factor put into the price forecast algorithm?
I have a project that greatly improves Bitcoin as magnet for development, infrastructure, paid order flow, and marketing. These advantages will scale linearly with market cap and thus marginalize altchains - even as they pioneer or subsequently adopt similar improvements. If the alternative technology extends Bitcoin or otherwise runs on the Bitcoin platform, then that will survive and prosper. Sidechains for Bitcoin, under somewhat stealthy development today, could provide the platform for branded coins and niche/innovative features.
In the wake of the rally now under way, I suppose that like in the November 2013 bubble, altcoins will be late to the party and fade as the bubble subsequently collapses. Assuming that altcoins as a sector are more volatile than bitcoin one could stay long in bitcoin for the moment. When the weekly price growth rate of the altcoin leaders meets or surpasses the bitcoin price growth, then switch to the altcoins you prefer, and sell at the peak, switching back long into bitcoin during the collapse.